CHROMATOGRAPHY Flashcards
is a technique in which the components of a mixture are separated based on differences in the rates at which they are carried through a fixed or stationary phase by a gaseous or liquid mobile phase
Chromatography
It is a phase that is fixed in place either in a column or on a planar surface
Stationary Phase
It is the phase that moves over or through the stationary phase carrying with it the analyte mixture. - It can be gas, liquid or a supercritical fluid
Mobile Phase
Stationary phase is held in a narrow tube
The mobile phase is forced through the tube under pressure or by gravity
Column Chromatography
Used for the separation of steroids, barbiturates, blood alcohol and lipids
Gas Chromatography
Two Types of Gas Chromatography
Gas Solid Chromatography
Gas Liquid Chromatography
Measure differences in absorption at the solid phase surface
the mobile phase is a gas, and the stationary phase is a solid that retains the analytes by physical adsorption
Gas Solid Chromatography -
Separation occurs by differences in solute partitioning between the gaseous mobile phase and the liquid stationary phase
the mobile phase is a gas, and the stationary phase is a liquid that is retained on the surface of an inert solid by adsorption or chemical bonding
Gas Liquid Chromatography
Mobile phase in gas chromatography
Chemically inert
Carrier Gas System -
is the most common mobile phase (argon, nitrogen, and hydrogen are also used)
Helium
is widely used measure the desirable flow through the column.
Classical Soap Bubble -
For high column efficiency, a suitably sized sample should be introduced as a “plug” of vapor.
Sample Injection System
is achieved by increasing the column temperature continuously or in steps during elution
TEMPERATURE PROGRAMMING
Most widely used and generally applicable detector for gas chromatography
Effluent from the column is directed into a small air/hydrogen flame
Flame Ionization Detector (FID)
one of the earliest detectors for gas chromatography
Consist of an electrically heated source whose temperature at constant electric power depends on the thermal conductivity of the surrounding gas
Thermal Conductivity Detector (TCD)